1. Field of the Invention
The invention relates to the field of interfacing digital computers, particularly microcomputers or microprocessors and to the field of microprocessors suitable for operation as slave units.
2. Prior Art
In computer applications and particularly with microcomputers and microprocessors, it is sometimes advantageous to employ a second microprocessor as a slave unit to a master microprocessor. Typically, the slave unit is programmed for specialized computations or tasks, thereby relieving the master microprocessor of these tasks and providing the master processor with a greater degree of freedom.
Since the slave unit for practical reasons, must be coupled to the common data bus shared by the master microprocessor, random-access memory (RAM) and other units such as a direct memory access (DMA) controller, the master-slave microprocessor protocol is an important consideration if effective utilization of the slave processor is to be achieved. Some of the advantages of the slave unit are lost if continuous intervention by the master microprocessor is required for all the activities of the slave unit.
With the described slave microprocessor and its protocol with the master microprocessor, the slave unit is readily controlled by the master unit, however, data transfer under the control of the DMA controller is possible without intervention by the master microprocessor.